膜蛋白质的静态定向质子脱的15N固态NMR光谱中的侧链共振
Christopher Aisenbrey1, Lydia Prongidi-Fix, Alexandre Chenal
1Insitut de Chimie, Universite de Strasbourg, CNRS UMR7177, 4 rue Blaise Pascal, 67070 Strasbourg, France.
Journal of the American Chemical Society
|April 21, 2009
概括
本研究介绍了一种使用固态NMR来区分蛋白质侧链和骨干信号的方法. 这种技术改善了对均 (15) N 标记蛋白质的结构分析,克服了赋值模两可.
科学领域:
- 生物物理学的生物物理.
- 结构生物学 结构生物学
- 核磁共振光谱学 核磁共振光谱学
背景情况:
- 质子解 (15) N 固态NMR对于分析蛋白质结构,动力学和膜拓学至关重要.
- 细菌对均 (15) N 标记蛋白质的过度表达导致脊柱胺和特定侧链 (Arg, Gln, Trp, Asn, Lys, His) 的标记.
- 侧链共振往往与频谱中的骨干胺基信号重叠,导致潜在的分配模两可.
研究的目的:
- 开发和演示一种方法来区分蛋白质侧链和骨干共振在15N固态NMR光谱中.
- 为了解决重叠共振的问题,这可能会使蛋白质结构分析复杂化.
- 提高膜蛋白和蛋白质域的结构和动态研究的准确性.
主要方法:
- 使用了质子脱的 (15) N 固态NMR光谱学.
- 综合交叉极化 (CP) 和哈恩回声脉冲序列.
- 应用实验和模拟的15N光谱进行分析.
- 研究的定向紫色膜,喉毒素T域和Bcl-x(L) 蛋白样本.
主要成果:
- 成功地区分了侧链和骨干气共振.
- 证明了结合CP和Hahn回声实验用于共振分配的有效性.
- 提供了清晰的光谱证据来区分复杂蛋白质系统中的重叠信号.
- 在多种不同的蛋白质结构中验证了该方法,包括膜蛋白.
结论:
- 结合CP和Hahn回声方法有效地解决了15N固态NMR中侧链和骨干信号重叠造成的模两可.
- 这种方法显著提高了统一 (15) N 标记蛋白质的结构和动态表征.
- 准确的共振分配对于生物物理研究中可靠的结构和动态解释至关重要.
相关概念视频
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
01:04¹³C NMR: ¹H–¹³C Decoupling
The probability of having two carbon-13 atoms next to each other is negligible because of the low natural abundance of carbon-13. Consequently, peak splitting due to carbon-carbon spin-spin coupling is not observed in spectra. However, protons up to three sigma bonds away split the carbon signal according to the n+1 rule, resulting in complicated spectra.
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
01:07Proton (¹H) NMR: Chemical Shift
Organic molecules primarily contain carbon and hydrogen atoms. While all the hydrogen isotopes are NMR-active, protium or hydrogen-1 is the most abundant. It has a significant energy separation between its nuclear spin states due to its large gyromagnetic ratio. As per Boltzmann's distribution, an increase in the energy separation implies a greater excess population of nuclei available for excitation, resulting in a strong NMR absorption signal.
Absorption signals of all the protium nuclei in a...
Absorption signals of all the protium nuclei in a...
01:12Double Resonance Techniques: Overview
Double resonance techniques in Nuclear Magnetic Resonance (NMR) spectroscopy involve the simultaneous application of two different frequencies or radiofrequency pulses to manipulate and observe two distinct nuclear spins. One important application of double resonance is spin decoupling, which selectively suppresses coupling with one type of nucleus while observing the NMR signal from another nucleus, simplifying the spectrum and enhancing resolution.
Spin decoupling is usually achieved by...
Spin decoupling is usually achieved by...
01:14NMR Spectrometers: Resolution and Error Correction
When magnetic nuclei in a sample achieve resonance and undergo relaxation, the signal detected in NMR is an approximately exponential free induction decay. Fourier transform of an exponential decay yields a Lorentzian peak in the frequency domain. Lorentzian peaks in an NMR spectrum are defined by their amplitude, full width at half maximum, and position, where the peak width is governed by the spin-spin relaxation time alone. In real experiments, however, the applied magnetic field is rendered...
01:19NMR Spectroscopy Of Amines
In proton NMR spectroscopy, primary amines and secondary amines showcase their N–H protons as a broad signal in the chemical shift range between δ 0.5 and 5 ppm. The exact position in this range depends on several factors, including sample concentration, hydrogen bonding, and the type of solvent used. Since amine protons undergo fast proton exchange in solution, the protons are labile and therefore do not participate in any splitting with adjacent protons. Thus, the observed peak is broad and...